1. Technical Field
The present invention relates to a method for production of a three-dimensional dyed macropattern in a web of web-shaped flexible material. The method comprises bringing at least parts of a pattern device, which has a three-dimensional macropattern of alternate raised macroportions and lowered macroportions, into contact with a dye-application device in such a way that a dye is applied to the pattern device only on the tops of the raised macroportions. The method also comprises bringing the web into contact with the tops of the dye-coated raised macroportions in such a way that dyeing of the web takes place in a dyed macropattern corresponding to the design of the tops of the raised macroportions. The web is moreover brought into contact with a bonding device which forms bonding points in the web and also three-dimensional bonding areas coinciding with the bonding points. The invention also relates to a device for manufacturing the web and also the web manufactured by means of the method.
2. Related Art
In the manufacture of, e.g., absorbent articles, it is known to mechanically emboss a three-dimensional pattern in one or more layer(s). It is also known to dye the embossed pattern so as to obtain a visually improved pattern.
It is also known to laminate two or more layers together in a multilayer web in order to manufacture the end product. In this way, a softer and more flexible end product is obtained than if a single layer with thickness and weight per unit area corresponding to those of the laminated product had been manufactured. It is known that the lamination of two or more tissue layers is effected by means of gluing. The glue can then be colored so as to dye those parts of the laminate which have been glued together. One problem with this technique is glue bleed-through, i.e., as the adhesive is pressed through the layer, the adhesive soils the counter-roller. Soiling of other machinery and parts in the process by adhesive is moreover a widely known problem.
A further problem with using adhesive is that hard crust-like surfaces appear on one or both side(s) of the layer, which can feel unpleasant for a user. The solidified adhesive may moreover be liquid-impermeable and can therefore give rise to liquid-permeability problems in the material. Other disadvantages of adhesive are that it is consumed in great quantities and therefore generates undesirable cost.
A further problem associated with the use of colored adhesive is that it can be difficult to combine with other joining methods, such as welding, as the risk of glue bleed-through increases and there is also a risk of the adhesive burning and soiling the machinery further.
All the previously known methods of dyeing and connecting a multilayer web comprise the step of dyeing the bonding points before or after the layers are connected. In the case of the bonding points being dyed before bonding takes place, the dye can flow out and cause a problem with an unclear pattern. When the bonding points are dyed after bonding has taken place, problems arise with the precision of the dyeing.
It is therefore desirable to find an improved method of dyeing and embossing a web. It is especially desirable to dye and join together a multi-layer web. The method should give an improved visual pattern irrespective of the thickness of the layers, but preferably for thin material. The desired product is to feel soft and comfortable to the user and to be aesthetically attractive by virtue of a three-dimensional dyed pattern. The pattern is to consist of the three-dimensional bonding areas which originate in the bonding points and also dyeing of the bonding areas and/or the bonding points.